In today's radio communications networks a number of different technologies are used, such as Long Term Evolution (LTE), LTE-Advanced, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile communications/Enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide Interoperability for Microwave Access (WiMax), or Ultra Mobile Broadband (UMB), just to mention a few possible implementations. A radio communications network comprises radio base stations providing radio coverage over at least one respective geographical area forming a cell. The cell definition may also incorporate frequency bands used for transmissions, which means that two different cells may cover the same geographical area but using different frequency bands. User equipments (UE) are served in the cells by the respective radio base station and are communicating with respective radio base station. The user equipments transmit data over an air or radio interface to the radio base stations in uplink (UL) transmissions and the radio base stations transmit data over an air or radio interface to the user equipments in downlink (DL) transmissions.
The WCDMA/High Speed Packet Access (HSPA) and LTE technologies have further evolved and are constantly evolving towards multi-carrier systems. A multi-carrier user equipment, which has multiple receivers or a wide band receiver, is typically able to measure on inter-frequency carriers without gaps. However such user equipments may still require measurement gaps, i.e. only receiving signals for performing measurements on, for performing measurements on inter-Radio Access Technology (RAT) carriers and also on the additional inter-frequency carriers. Inter meaning different frequencies. The additional inter-frequency carriers are those which cannot be measured without gaps. For example in Dual Cell High Speed Uplink Packet Access (DC-HSUPA), the user equipment may measure on a secondary DL carrier, which is adjacent to a primary DL carrier without gaps. But the same user equipment requires gaps to measure on inter-frequency carrier which is non-adjacent to the primary DL carrier or belong to another band, e.g. a Band B if the user equipment supports band B. In prior art multi-carrier system when the user equipment is requested to read target cell's system information the autonomous gaps are created by the user equipment on the primary DL carrier or Primary Cell (PCell). The autonomous gaps are created on the primary DL carrier even if the user equipment is Carrier Aggregation (CA) capable and has multiple receiver chains e.g. inter-band CA. In this case the primary DL carrier and the secondary DL carrier operate on different bands e.g. the primary DL carrier and the secondary DL carrier on band A and band B respectively using separate chains. For example in prior art even if the user equipment reads system information of the target cell on the secondary DL carrier the autonomous gaps are always created on the primary DL carrier. Thus, today user equipments perform retrieval of System information during measurement gaps, e.g. autonomous gaps, on the primary DL carrier, which retrieval causes interruption in the data retrieval on the primary DL carrier. Thus, the experienced performance of the radio communications network is reduced.